This invention relates to a method of measuring the blood pressure by means of a blood pressure cuff of a new type.
The blood pressure is usually measured by means of a blood pressure cuff which is placed around the patient's upper arm (or sometimes thigh) and which is kept in position by means of a bur fastener. The systolic and diastolic pressure can be measured by the aid of an air pump intended to set the cuff under pressure and a manometer.
Today a standard cuff is used for measuring the blood pressure of all patients independently whether the patient's arm is slender or thick. The width of this standard cuff is about 12 cm. Due to the fact that there is a soft tissue between the blood vessel and the bone in the middle of the arm (or thigh) the real blood pressure measured with the same cuff is ambiguous for different arm thicknesses despite the same read pressure. Thus, a person having a slender arm will have a relatively low read pressure whereas a person having a thick arm will show a relatively high read pressure in spite of the persons in reality having the same blood pressure. In the latter case a higher pressure is required in the cuff to reach, i.e. actuate, the blood vessel. A corresponding lower pressure is required for the slender arm in order to actuate the blood vessel. These conditions mean that the manometer is deflected which means in reality errors to the order of 5-10 mm Hg as to both the systolic and diastolic pressure.
The limit of treating a patient for e.g. increase of blood pressure can be dependent on the fact whether the patient has 95 or 100 in the lower pressure, i.e. the diastolic one. Thus, the error margin of using this standard cuff is many times quite decisive whether a patient is considered as sick or not sick and is to be treated or not.